The arrival of dystopian scifi video game Mass Effect has us reaching for our Prozac . . . and our controllers. The darker and weirder the world a video game gives us, the better. Whether it involves an alien invasion, or a maniacal artificial intelligence, we love games that crush our dreams in an orgy of hopeless shootouts. Mass Effect is just the latest in a whole crop of disturbing, scifi thriller games you should stockpile for the long, cold months ahead.

Half-Life: The original Half-Life came out in 1998, and it's sequel Half-Life 2 came out in 2004. The extremely popular game has spawned numerous "mini-sequels," including Half-Life 2: Episode 1 and Episode 2, and the spinoff title Portal.

In the game, you play Dr. Gordon Freeman, a scientist who unwittingly tears open a dimensional portal during a routine experiment at a facility in the Black Mesa Research Facility in New Mexico. Aliens begin pouring through the newly opened portal, and you find yourself both the target of these creatures, and of government forces who are trying to hush up the incident. You end up surviving (the sequels wouldn't make much sense otherwise) and things get continually worse. By the time Half-Life 2 begins, the Earth has been changed into a dystopian world that is slowly being de-terraformed into a wasteland. Oceans are being drained, buildings taken apart, and the place is full of both alien and humanoid forces who want to have your liver for dinner.

Halo: Halo 3 came out in September, to massively sales and fanboys complaining that it just "wasn't enough," but developer Bungie has created a fully realized universe within in the game.

Halo takes place in the distant future where the human race is in the middle of a bitter war with an alien race called The Covenant. You play "Master Chief," a genetically engineered supersoldier (called a Spartan) who dons battle armor and serves as humanity's last hope. As the game progresses, you discover that the Covenant have found a giant ring-like object (a Halo) left behind by an ancient alien race called The Forerunners. If activated, the Halo will act as a deadly weapon, able to destroy entire planets. Much like Luke destroying the Death Star, you have to destroy the Halo and make sure the Covenant don't win. The Earth in Halo is brutally invaded by the Covenant, where they lay waste to entire continents with massive weapons, turning all of the land into glass. Cities have become battlefields, and most of the citizens have been wiped out, or are in deep hiding. It's not a pretty site when you see nukes going off all over the planet, and it's even less pretty when you have to go down there. Even if you manage to save the world, it's going to look like a wasteland when you're done.

BioShock: One of the most imaginative games to come along in years isn't set in the future at all, but in a bizarre undersea city that re-imagines the future of the past, and combines a steampunk science fiction approach with genetic modification technology.

In BioShock the game controls Jack, a passenger aboard a plane in 1960. Disaster strikes and the plane plummets into the ocean, killing everyone aboard except you. You swim to a nearby tower poking out of the dark waters, and inside find a bathysphere that takes into Rapture, a full-sized city built secretly on the ocean floor in 1946. Through a series of audio recordings and newsreel style videos, you're shown how meglomaniacal millionaire Andrew Ryan built the city to get away from what he saw as the oppressive rules of government and religion. He envisioned Rapture as an undersea utopia, but it didn't take long for things to unravel. By the time Jack arrives in the city, it's clear that the place is falling apart, and most of the popular are dead. The only remaining inhabitants are "Splicers," genetically mutated humans who are murderous and insane, and a few human holdouts who have barricaded themselves into the few remaining safe places in the city. You become trapped in a battle between the leader of the black market, Atlas, and the insane Ryan himself. As the game progresses, you acquire raw genetic material that you can use at upgrade stations to modify your genetic template, meaning you can give yourself telekinesis, the ability to turn invisible, or the power to shoot flames from your hands. It's sort of like having Heroes on tap. You come to appreciate the beautiful disaster that Rapture has become, with the sea attempting to overtake the city that has become trapped in time.

Portal: Strictly speaking, Portal was meant to be a small one-note spinoff set in the Half-Life universe featuring a small game called Narbacular Drop that Half-Life developer Valve had acquired. It was included in The Orange Box, a game set Valve released last month that included Half-Life 2, Episode 1, Episode 2 and Portal. Portal has overwhelmingly been the smash hit of that set.

In Portal you play Chell, a female test subject for Aperture Science, Inc. (a company in the Half-Life universe) who wakes up inside a gigantic maze and coached (or tortured, depending on your views) by an artificial intelligence called GLaDOS (Genetic Lifeform and Disk Operating System). GLaDOS puts you through a series of testing chambers designed to help you learn how to use the "Portal" gun, which can create entrace and exit wormhole portals on walls, ceilings, and floors. Each chamber challenges you further with increasingly hard puzzles that you have to solve using the Portal gun in order to escape. As the game goes on, you notice that GLaDOS is a bit off her rocker, and all of the human observation posts are empty. In fact, she starts promising that cake will be waiting for you if you can complete the test course. Later you're able to slip behind the scenes and find some graffiti from a previous test subject telling you that the cake is a lie. Although if you finish the game, you find out that she might not have been lying all along. It's all immortalized in a song that GLaDOS sings you over the closing credits, which you can watch below.